Method of making propeller blades



June 24,1947. BNEDMANN 2,422,910

METHOD O MAKING PROPELLER BLAES Filed Jan. e, 1944 2 sheets-sheet 2 FIG 2 /Z H?.

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Patented June 24, 1947 2,422,810 METHOD OF MAKING PRPELLER BLADES Julius B. Tiedemann, Milwaukee, Wis., assigner To A. 0. Smith Corporation, Milwaukee, Wis., a corporation of New York Application January 6, 19447, Serial No. 517,207

i claim. (o1. zii-156m halves welded together along longitudinal lines in the foil surface and is more particularly concerned with the forming of the separate leading and trailing edge sections of the blade.

The principal object of the invention is to provide a method of forming an edge section of the blade with a longitudinally tapered thickness, a heavy edge portion, varying width and with the twist of the blade.

A more specific object is to provide a'method for forming an edge section with the blade twist.

Other objects and advantages of the invention will be set forth in the following description of a preferred manner of carrying out the invention illustrated in the drawings.

In the drawings:

Figure 1 is a perspective view of a blank from which one half of the blade is made;

Fig. 2 is a side elevation showing the rolling of the blank to tapered thickness;

Fig. 3 is a central transverse section showing the cross-sectional shape of the body of the blank of the folding operation;

Fig. 'l is a similar view showing the completion of the forming;

Fig. 8 is a transverse section through the shank showing the operation of Fig. '7;

Fig. 9 is a side elevation of the blade half after the forming operation of Figs. l and 8;

Fig. 10 is a central transverse section showing the side forming operation;

Fig. 11 is a similar view illustrating the final twisting of the blade section; and

Fig. l2 is a perspective View of an assembled and welded blade.

In carrying out the invention, it is possible to start with either a blank of rectangular rolled plate of a thickness approximating that of the shank of the blade, or preferably, to start with a rolled plate I having a"wicle central longitudinal raised portion 2.

In the first rolling operation, the raised portion 2 is flattened out at the shank end of the blade and it is narrowed to the shape of a ridge 3 extending longitudinally of the body of the blank at approxi'mately the center line. At the same time, the specially contoured rolls 4 taper the thickness of the body portion of the blank longitudinally to correspond with the desired tapered thickness of the same portions of the blade from a maximum thickness at the shank to a minimum thickness at the tip.

In the next operation either a press or a roll is employed to further shape the ridge 3 and to provide a channel 5 on its back side, which constitutes the inside of the iinished blade. The location of the ridge 3 and channel 5 in the blank should correspond to either the leading or trailing edge of the nished blade and is preferably on the longitudinal center line of the blank-so that when the latter is folded its side edges will extend along the center line of the foil surfaces of the blade.

The final forming of the ridge 3 is illustrated in Fig. 5 where, after punch 6 has been lower onto the blank, the lower supporting die members 1 and 8 are moved toward one another to extrude the ridge downwardly from the plane of the blank.

The folding of the blank is accomplished by a male and female die arrangement in which the blank is supported on the female die 9 having a longitudinal recess with upper corners I0 cut away on a large radius. A blank holder II extends upwardly in the die recess and has a groove for receiving the ridge 3 of the blank. The punch I2 has a blunt nose engaging in the channel 5 of the blank, and downward movement of the punch I2 forces the blank into the die recess as the blank holder II recedes. The sides of the blank are folded inwardly to vertical position following the side Wall of the die recess.

In the shank end of the blank, there being no ridge 3 and channel 5, the die 9 and punch I2 are formed semi-circular and the blank holder II provides a part of the bottom of the die recess.

The formed blank has the shape shown in Fig. 9.

'I'he blank is then placed on a fixed punch I3, and the sides are pressed inwardly by laterallir movable dies I4 and |15, as illustrated in Fig. 10.

The blankis given the final twist of the blade by pressing it onto a xed punch I6 embodying the blade twist and pressing the sides inwardly by laterally movable dies I'I and I8, as illustrated in Fig. 11. The removal of the blank from the twisted punch I6 can be effected by a longitudinal unthreading, the spiral nature of the twist and the tapered thickness of the punch making this possible.

The side edges of the blank are then sheared for welding to similar edges of a complementary blank I9 along the longitudinal center line of the blade. The welds 20, shown in Fig. 12, may be made by a fusion Welding operation as set forth in the copending application of Warren F. Heineman, Serial No. 529,951, filed April 7, 1944, for Airplane propeller, blade andv method ofV making Y the same and assignedto the assignee of the present invention.

The invention may be employed in the forming of edge sections for othertypes ofy bladeonstruction than that illustrated, it being possible to fabricate the blade of longitudinal partsrwyelded together along transverse. lines,v one -or A moreof ,-die.members constituting a punch'rtting in the the parts having sections formed as herein ,de-"' scribed.

Various modes of carrying out the invention may be employed within the scope of theaccompanying claim.

I claim:

In theA fabrication-` ofhollow metal propeller d blades,l from a plurality of partsincluding -two or more longitudinallyextending sections Welded together along. longitudinalzs'eamsin the respective foil surfacesof the blade; the methodoflform` ing an edge section comprising rolling. a; plate metal1 ,blank longitudinally tntaper the; same in channel of the blank,`dra'wing lsaid blank between dies while thus clamped t0 fold the sides of the `4blank along said ridge to substantially V-shape, pressing the blank between laterally movable dies and upon an internal mandrel to bring the sides into air Vfl'oilnshape and provide the blade twist y.therein, ;and trimming the edges of the blank for .welding.

JULIUS B. TIEDEMANN.

REFERENCES CITED The following references are of record in the @fue of this; Patent UNITED STATES PATENTS Number tName Date 25 2,231,772 Y. Nelson Feb. 11, 1941 1,988,202 Hoover Jan. 15, 1935 51,501,606 Leitner Ju1y 15, ,1924 

